Signs of valve micro welding

[NonSyncro]

Finally got round to pulling the head for a valve stem seal job on my series 3 2.25 petrol land rover. Since it was manufactured in 1974 I presume the valve seats wont have been hardened, however the previous owner used castrol valvemaster (lead replacement additive) when filling up, and I was assured that the valves would be fine. Further inspection revealed the exhaust valve seats have small depressions, less so on the intake valve seats. However the valves themselves appear to be ok.





Is this micro welding? And if so, it doesn't say much for lead replacements
Hardened valve seats would be the obvious solution, however I need the landy back on the road soon. Does anyone have a ballpark figure for how much hardened valve seat fitting costs?

Thanks
NonSyncro